after a crash course, thanks to some helpful people here and there, i finally managed to stablish a solid bridge between realflow and max, so i wanted to share, because i had a lot of frustration these days. so heres what i do:

1.make a low poly version of my scene, the part that will interact with the fluids, and export a SD file with the realflow plugin. my 3ds max unit scale is set to 1 max unit represent 1cm, since realflow deals with max generic units, not the physical units that are just a override, so i can simulate in the correct scale inside realflow

2.inside realflow, first of all i set my geometry scale to 0.01, then you import your SD file, and you'll have your scene correctly sized in RF viewport. when you import geometry from max onto realflow, it will consider the max generic unit, no matter what override unit you're using. so if i make a 100cm (1m) box inside max, and my scale is set to 1unit = 1cm, the box will be 100 units, and realflow will take it as 100m, not 1m as it should, thats why i set geometry scale to 0.01. that could easily be fixed in max, by setting 1 unit = 1m, so you wouldnt have to worry about scaling geometry in realflow, but that way, things would be fucking big on max, thats why i dont do it. also, i believe max is set by default to 1 unit = 1 inch, and not 1cm, i switched it first of all because i deal with metric units, and also, because you couldnt scale it properly in realflow, like the geometry scale can be set only like 2 or 3 units after the dot, and experimenting, i realized that you needed a geometry scale of something like 0.0265 (i dont remember the value right now) and realflow would round it, so you would never have the exact size. changing max generic unit to match 1cm, i easily fixed that.

3.now you can start setting up your fluid, and simulate it. make sure you export the grid emitter particle .bin files, and not just the grid cache (.gdc). for some reason i had it disabled in my export central, but its necessairy if you're importing your particles to max. im basically using hybrido for everything, so i simulate the fluid, splash, foam and mist, even if im not gonna use some of them, they are there if needed. the hybrido workflow is very well covered in youtube, and some paid tutorial channelsl like digital tutors. the only thing i do different, is that i mesh my grid simulation using renderkit mesher inside realflow, and not grid mesh. i found the grid mesh to be way too ugly. you need a combination of generic displacement maps in order to get useable results, its almost like you're using realwave, so its pointless to make a fully detailed hybrido sim and mesh with grid mesher. i should also mention that i mesh my grid particles and splash particles together, i found that they will give your fluid more realism if meshed. also, im gonna mesh it with max renderkit, so im just meshing inside realflow to test parameters (they are pretty much the same in max rfrk) and having a pre-made mesh available if needed.

4.back inside max, with rfrk mesher 2, i import my .bin files for the grid particles and splash particles, again they will be meshed together. so i just instance my mesher2 map to a material slot to set up the parameters that i found to be the best while meshing inside realflow. after that i do some test renders to make the last adjustments on my mesh. better disable final gather, raytracing, and everything that can slow down your render, since its meant just to see how your mesh looks. also notice that when you import your particles to max viewport, they will be in the correct size, thanks to our scaling adjusts. if you dont want to use the max rfrk mesher, or want to compare the result, you can import your .bin mesh you did with realflow, using the realflow plugin.

5.when satisfied with the result, you can apply a material and render your main fluid mesh. i render 3 passes, 1 for the main mesh (core fluid + splash), then i use particler2 to import foam particles but not mesh them, and render them with krakatoa, and last thing i use the rfrk cloud to import my mist. then you can composite them together. i personally use fusion :)

in addition, you can use realflow to generate wet maps for the geometry, aswell as displacement maps, for fine detail. i personally just generate wet maps. i do displacement by hand with a combination of smoke/noise maps for bump and displacement slots.

another tip to make foam when you dont have automatic foam creation (for example with realflow 4), you can import your fluid particles, and render them using krakatoa's color by vorticity. make the vorticity color white, and the rest black, so you'll get a foam like pass to composite later.

please correct me if i said something wrong, and tell me if this can help.
cheers!

Thats a very difficult question to answer, as every simulation or scene is different in scale en splashiness (is this a real word?).

What i tend to do, when there aren't enough particles for krakatoa to render a decent picture, is partitioning the particles with krakatoa. (its a sort of duplicating tool, wich displaces every copy of a particle a little bit, so you can get a more dense particle cloud)

I don't know if you know how to do that, but there are tutorials on the net
--> basic workflow: partition the particles, bring them back in with a krakatoa prt loader in pflow an play with some settings to get the right result.

Hi I'm having issues with scaling between max and RF 2012I have set max units as 1 unit = 1cm (same for system units)I set preferences in RF to scale .01 but it imports x100 too big.I cant change the preferences to scale any less in RF so i have had (workaround)to make the objects x100 smaller in max ie less than 1mmWhy is this happening? The scale factor does not seem to have any effect on the object size. If i change it to 1 it still imports the SD file at the same size as when it is .01.any ideas?